Dongfeng Peugeot Citroen Automobile, PSA Group's joint venture with Dongfeng Motor in China, continues to lose market share, with August sales tumbling 38 percent to 26,205 vehicles.
In the first eight months, the partnership's sales plummeted 46 percent from a year earlier to 195,138, according to figures disclosed by Dongfeng, a state-owned Chinese company.
Dongfeng didn't release sales results for individual models produced by the joint venture.
PSA expects the locally built Peugeot 5008 SUV, which hit the market in June, to reverse the sales slump.
The venture, based in the central China city of Wuhan, assembles Peugeot and Citroen cars and light trucks.
PSA also runs a joint venture with state-owned Chinese automaker Changan Automobile in China.
Changan PSA, located in the south China city of Shenzhen, builds the Citroen DS models. The latest sales results for the joint venture are not available since Changan stopped releasing results in July.
In the first six months, Changan PSA's sales tumbled 64 percent year on year to only 3,157 vehicles, according to Changan.
PSA does not disclose sales of its two joint ventures in China.
While PSA's sales weakened, the overall Chinese light-vehicle market grew the past three months.
In August, car and light-truck deliveries in China rose 4.1 percent year on year to approach 1.88 million boosted by strong crossover and SUV demand. Through August, light-vehicle deliveries across the country increased 2.2 percent to top 14.8 million vehicles.